Laser pulse drilling processes are used to form bores of small diameter, for example, in hollow workpieces. Turbine blades in particular have a number of such fine bores for passage of cooling air which can be made automatically by this process with high positional accuracy.
However, the bores must also comply with precise tolerance with regard to their diameter to produce the cooling air flow rate necessary in operation. For example, if the individual diameters of the bores are too small, this can lead to unacceptable overheating of the turbine blades and to their failure. In turn, this can lead to the failure of the entire gas turbine system. It is therefore important to check the dimensional compliance of the bores produced. This has been done heretofore by inserting measuring rods manually into the individual bores. This process involves an extraordinarily high expense which is associated with excessively high costs.